LEC 17: Anxiety disorders

What are anxiety disorders?

• category in the DSM-5 that includes disorders that share features of excessive fear and anxiety and related behavioural disturbances

• includes specific phobias, social anxiety, etc.

Anxiety vs. Fear

anxiety:

• apprehension/worry about real or perceived future threats

fear:

• emotional and physiological reaction to real or perceived immediate threats

Fear and the amygdala

• the amygdala has direct access to sensory information and this allows it to quickly react to dangerous stimuli

• the amygdala is active during situations of anxiety and phobia

• the amygdala can activate the sympathetic nervous system

Panic disorder

• characterized by recurrent and sudden debilitating panic attacks that come on unexpectedly

• in Canada, about 3.7% of people will be diagnosed with a panic disorder in their lifetime

• female to male ratio is 2:1

Symptoms of a panic attack

• palpitations, pounding heart, or accelerated heart rate

• sweating

• trembling or shaking

• sensations of shortness of breath

• nausea

• chest pain or discomfort

Neurobiology of a panic attack

• highly heritable

• the only gene clearly linked to the disorder is COMPT, which codes for the enzyme Catechol-O-methyltransferase, an enzyme that degrades catecholamine neurotransmitters

Generalized anxiety disorder

• characterized by excessive anxiety, worry, and rumination

• in Canada, the 12-month prevalence of GAD in people aged 15 or older is 5.2%

• particularly pronounced among young women (11.9%)

Symptoms of GAD

• restlessness

• being easily fatigued

• irritability

• sleep disturbance

• difficulty concentrating or mind going blank

Neurobiology of GAD

• people with GAD are said to be “autonomic restrictors”, meaning that their sympathetic nervous system is actually less responsive to stressors

• people with GAD show increased activation of the frontal lobes in response to stressful stimuli

PD vs. GAD

GAD:

• a disorder that’s primarily anxiety-based

• increased PFC activity and reduced SNS activity

PD:

• a disorder that’s primarily fear-based

• decreased PFC activity and increased limbic and SNS activity (during panic attacks)

Treatments for anxiety

Pharmacological:

• drugs that treat anxiety are called anxiolytics

  • fast-acting favoured for PD, slow-acting favoured for GAD

• benzodiazepines are drugs that are agonists at GABA receptors

  • Xanax (alprazolam), Valium (diazepam)

• antidepressant medications are also quite effective

Non-pharmacological:

• Cognitive Behaviour Therapy

• Eye Movement Desensitization and Reprocessing (EMDR) Therapy

The fear response

• starts with activation of the amygdala, which then activates the sympatho-adrenomedullary (SAM) axis

• this brings about the ‘fight or flight’ response